The photocatalytic degradation of carbamazepine and prediction by artificial neural networks

The three layer artificial neural network model was applied to predict the degradation efficiency for carbamazepine in photocatalytic oxidation under UV radiation. Titania–zirconia was employed as a catalyst for the photooxidation. The catalyst was prepared using titanium isopropoxide and zirconium oxychloride by sol–gel method and characterized by transmission electron microscopy and BET analysis. Different process parameters such as, initial concentration of carbamazepine, pH of the solution, catalyst concentration and time of UV irradiation were employed as the input to the artificial neural network model and the output of the network was degradation efficiency of carbamazepine. The multilayer feed-forward networks with the Levenberg–Marquardt (trainlm) backpropagation training algorithm was used for the network training. The smallest mean square error was obtained for three-layer network with ‘logsig’ transfer function and five neurons in the hidden layer gave optimal results. A comparison between the predicted values and selective experimental data of degradation efficiency showed a high correlation coefficient (R²) of 0.997.     

高级氧化法处理难降解有机废水研究进展

综述了几种高级氧化法包括Fenton法、O3/UV法、O3/H2O2法、UV/H2O2法、O3/UV/H2O2法和TiO2法的反应机理、特点及在难降解有机废水处理中的应用进展,并对高级氧化法存在的问题及今后的研究方向进行了探讨。     

磁强化次氯酸钠氧化法处理邻硝基苯酚废水的实验研究

利用磁强化次氯酸钠氧化法对邻硝基苯酚废水进行了处理实验研究。结果表明,对于质量浓度为250mg／L、CODCr为2000mg／L、色度为150倍的100mL邻硝基苯酚废水,当次氯酸钠（2．5％）用量8mL、颗粒活性炭用量200mg、溶液pH为6．0、反应时间5min时,邻硝基苯酚的去除率达94．4％,CODCr的去除率达94．2％,色度的去除率达100％。采用外加磁场,当磁场强度为60mT时,邻硝基苯酚和CODCr达到相同的去除率,反应时间缩短了3min,显著提高了反应效率。同时对磁强化氧化法的机理进行了理论上的分析。     

Removal of Volatile Organic Compounds from polluted air

Volatile Organic Compounds (VOCs) are among the most common air pollutants emitted from chemical, petrochemical, and allied industries. VOCs are one of the main sources of photochemical reaction in the atmosphere leading to various environmental hazards; on the other hand, these VOCs have good commercial value. Growing environmental awareness has put up stringent regulations to control the VOCs emissions. In such circumstances, it becomes mandatory for each VOCs emitting industry or facility to opt for proper VOCs control measures. There are many techniques available to control VOCs emission (destruction based and recovery based) with many advantages and limitations. Therefore, deciding on a particular technique becomes a difficult task. This article illustrates various available options for VOCs control. It further details the merits, demerits and applicability of each option. The authors hope that this article will help in critically analysing the requirements and accordingly decide on the appropriate strategy to control VOCs.     

Concurrent nitrate and Fe(III) reduction during anaerobic biodegradation of phenols in a sandstone aquifer

The biodegradation of phenols (5, 60, 600 mg l⁻¹) under anaerobic conditions (nitrate enriched and unamended) was studied in laboratory microcosms with sandstone material and groundwater from within an anaerobic ammonium plume in an aquifer. The aqueous phase was sampled and analyzed for phenols and selected redox sensitive parameters on a regular basis. An experiment with sandstone material from specific depth intervals from a vertical profile across the ammonium plume was also conducted. The miniature microcosms used in this experiment were sacrificed for sampling for phenols and selected redox sensitive parameters at the end of the experiment. The sandstone material was characterized with respect to oxidation and reduction potential and Fe(II) and Fe(III) speciation prior to use for all microcosms and at the end of the experiments for selected microcosms.The redox conditions in the anaerobic microcosms were mixed nitrate and Fe(III) reducing. Nitrate and Fe(III) were apparently the dominant electron acceptors at high and low nitrate concentrations, respectively. When biomass growth is taken into account, nitrate and Fe(III) reduction constituted sufficient electron acceptor capacity for the mineralization of the phenols observed to be degraded even at an initial phenols concentration of 60 mg l⁻¹ (high) in an unamended microcosm, whereas nitrate reduction alone is unlikely to have provided sufficient electron acceptor capacity for the observed degradation of the phenols in the unamended microcosm.For microcosm systems, with solid aquifer materials, dissolution of organic substances from the solid material may occur. A quantitative determination of the speciation (mineral types and quantity) of electron acceptors associated with the solids, at levels relevant for degradation of specific organic compounds in aquifers, cannot always be obtained. Hence, complete mass balances of electron acceptor consumption for specific organic compounds degradation are difficult to confine. For aquifer materials with low initial Fe(II) content, Fe(II) determinations on solids and in aqueous phase samples may provide valuable information on Fe(III) reduction. However, in microcosms with natural sediments and where electron acceptors are associated with the sediments, complete mass-balances for substrates and electron acceptors are not likely to be obtained.     

高锰酸盐指数法对石油类物质氧化率的研究

高锰酸盐指数法可用于监测地面水的有机污染程度,但它对石油类物质的氧化率很低,监测结果不能正确反映以石油类物质为主要污染物的地面水的污染状况,如用测得的高锰酸盐指数来确定ＢＯＤ５的稀释倍数,则会导致稀释倍数偏小。     

Polychlorinated biphenyls-containing electrical insulating oil contaminated soil treatment with calcium and magnesium peroxides

Calcium and magnesium peroxides were applied for the treatment of soil contaminated by polychlorinated biphenyls-containing electrical insulating oil (Aroclor 1016). The removal of PCB-containing electrical insulating oil was achieved with the addition of either calcium peroxide or magnesium peroxide alone and dependent on dosages of the chemical. A 21-d treatment of 60% watered soil with the moderate addition (chemical/oil weight ratio of 0.005/1) of either calcium peroxide or magnesium peroxide resulted in nearly complete (96 ± 2%) oil removal, unsubstantial increase in soil pH and almost no changes in oxygen consumption and dehydrogenase activity, making it suitable for the soil decontamination.     

味精废水厌氧氨氧化生物脱氮的研究

采用厌氧氨氧化工艺(ANAMMOX)处理味精废水,结果显示,总氮容积去除负荷可达457 mg·L-1·d-1,高于传统硝化-反硝化工艺,可成为传统硝化-反硝化工艺的替代技术.厌氧氨氧化菌对NO2--N的耐受范围为96.5～129 mg·L-1.受基质NO2--N抑制后,厌氧氨氧化反应器难以自行恢复,将基质浓度稀释到临界浓度以下则可恢复效能.反应器对进水cNO2-N/cNH4 -N比值有一定的适应能力.在所试的进水cNO2--N/cNH4 -N比值(1.0～1.4)范围内,出水基质浓度基本保持不变.     

长时间服役的进口锅炉T91炉管失效行为研究

针对某进口亚临界锅炉三级过热器T91炉管失效事件,通过对其进行硬度、金相组织和SEM扫描电镜分析找出导致爆管的原因,并根据高温氧化皮厚度对其进行蠕变剩余寿命评估,结果表明该段T91管材爆管类型为典型长期过热爆管,炉管长期处于较高温度运行导致组织老化严重,力学性能下降,引起材料蠕变损伤,导致长期过热爆管,经计算其蠕变剩余寿命已达到寿命极限。本文对该锅炉防止类似事故具有重要作用,并对国内其他同在二十世纪90年代开始服役的T9彳炉管具有重大的参考价值和借鉴意义。     

Differences of the oxidation process and secondary organic aerosol formation at low and high precursor concentrations

Current atmospheric quality models usually underestimate the level of ambient secondary organic aerosol(SOA), one of the possible reasons is that the precursors at different concentrations may undergo different oxidation processes and further affect SOA formation. Therefore, there is a need to perform more chamber studies to disclose the influence. In this work, SOA formation over a wide range of initial precursor concentrations(tens of ppb to hundreds of ppb levels) was investigated in a 30 m3 indoor smog chamber,and mainly through the analysis of multiple generations of VOCs detected from HR-To FPTRMS to expound the difference in the oxidation process between low and high precursor concentrations. Compared to high initial concentrations, gas-phase intermediates formed at low concentrations had a higher intensity by about one order of magnitude, and the lowvolatility compounds also had a higher formation potential due to the competition between semi-volatile intermediates and precursors with oxidants. In addition, the formed SOA was more oxidized with higher f44 value(0.14 ± 0.02) and more relevant to real atmosphere than that formed at high concentrations. This work should help to deeply understand SOA formation and improve the performance of air quality models for SOA simulation.